In the UMTS (Universal Mobile Telecommunications System) network, the specifications of long term evolution (LTE) have been drafted for the purpose of further increasing high speed data rates, providing lower delays and so on (see non-patent literature 1). Also, the specifications of LTE-A (also referred to as LTE-advanced, LTE Rel. 10, 11 or 12) have been drafted for further broadbandization and increased speed beyond LTE (also referred to as LTE Rel. 8 or 9), and successor systems of LTE (also referred to as, for example, FRA (Future Radio Access), 5G (5th generation mobile communication system), LTE Rel. 13 and so on) are under study.
Now, accompanying the cost reduction of communication devices in recent years, active development is in progress in the field of technology related to machine-to-machine communication (M2M) to implement automatic control of network-connected devices and allow these devices to communicate with each other without involving people. In particular, 3GPP (3rd Generation Partnership Project) is promoting the standardization of MTC (Machine-Type Communication) for cellular systems for machine-to-machine communication, among all M2M technologies (see non-patent literature 2).
In the course of standardization, various functions which terminals for use in MTC (MTC terminals) are also being studied, and, for example, a study is in progress to limit the transmitting/receiving bandwidth of terminals in order to reduce the cost. For another example, given that MTC terminals may be located in places where the MTC terminals suffer significant building penetration loss and have difficulty making radio communication, such as the depths of a building, the basement, and so on, MTC terminals that are directed to achieving enhanced coverage (coverage enhancement) are also under study.
Based on the above two examples, MTC terminals (MTC UEs (User Equipment)) can be divided into the following four types: (1) terminals without limits on the transmitting/receiving bandwidth and without coverage enhancement functions; (2) terminals with limits on the transmitting/receiving bandwidth and without coverage enhancement functions; (3) terminals without limits on the transmitting/receiving bandwidth and with coverage enhancement functions; and (4) terminals with limits on the transmitting/receiving bandwidth and with coverage enhancement functions. MTC terminals are being studied for use in a wide range of fields, such as, for example, electric meters, gas meters, vending machines, vehicles and other industrial equipment.
As a method of coverage enhancement, it may be possible to apply repetitious transmission (repetition), which improves the received-signal-to-interference-plus-noise ratio (SINR) by repeating transmitting the same signal over multiple subframes in the downlink (DL) and/or in the uplink (UL). For example, when a radio base station (eNB: eNode B) transmits a predetermined signal in repetitions, an MTC terminal applies power coupling to the signals received, and performs receiving processes (demodulation, decoding, etc.).